The present invention relates to automatically controlled fluid-flow, including faucet-sink systems, and encompasses more generally control systems for fluid flow and dispensing means. The prior art in this area is extensive, detailed and sophisticated. See for example, U.S. Pat. Nos. 3,480,787, 3,491,381, 3,575,640, 3,670,167, 2,738,448, 3,419,188, 4,309,781 and 4,373,471. The problem to which the present invention, as well as the above-cited prior art inventions pertain, is one of some importance, namely the provision of automatic means for controlling the flow of fluids such as water, with the consequent saving of energy, by providing water at sinks and similar devices only when actually needed or being used. In addition to the potential to save millions of gallons of water a day, the energy savings provided in the reduction of the amount of water required to be heated to desired temperatures is manifest, as is the savings in oil, gas and electrical energy utilized to heat the water.
A brief description of a number of the previously mentioned prior art will now be given.
Bokser, U.S. Pat. No. 2,738,488 discloses a system, for automatically flushing a toilet, whereby a user who either sits on a toilet or approaches a urinal breaks a light beam path to a photosensor, whereby the system is placed into a first condition for detecting restoration of the light beam to the photosensor when the user leaves the urinal or toilet. When the latter occurs, the system responds by going into a second condition for operating a valve for a predetermined period of time to flush the toilet or urinal, and thereafter await the next user.
Johansen, U.S. Pat. No. 3,480,787, in one embodiment teaches the application of a light transmitter 28 juxtaposed to a light sensor 29 at a level higher than a nozzle 30 and at a slight distance to its side of the vertical axis of the nozzle. The principal focus of the transmitter 28 and sensor 29 coincide at a point 31 (see FIG. 3) in a region at a level below the outlet of the faucet and laterally in relation to a vertical axis of the faucet. When a "user's" hands are placed below the faucet 30, light from transmitter 28 is reflected from the bands to the receiver 29, whereby a control circuit 25 responds to the detected reflected light for turning on a solenoid valve 21 to permit water to flow from faucet 30, when the hands are removed from the sink, light is no longer reflected to the receiver 29, and in response, control circuit 25 operates to turn off valve 21.
Cathcart, U.S. Pat. No. 3,491,381 discloses a system controlling the flow of water into a sink including an electric lamp mounted on one side of the sink and a photosensor on the opposite side for detecting a light beam from the lamp along a beam path disposed in front of the water path in juxtaposition thereto. When a user puts his hands into the expected water path, the light beam is broken, and the system responds by operating a solenoid valve to turn on the flow of water. A fail safe feature for preventing water flow if the lamp 18 failed, includes a resistive heater 38 in series with the lamp 18 for heating a bimetallic switch 40, 41. If the lamp 18 fails, power to heater 38 is interrupted, causing the bimetallic switch 40, 41 to cool and open its contacts, thereby preventing the system from turning on the solenoid valve. However, if the contacts 40, 41 in time become "pressed together" due to current transients, the fail safe feature will be rendered inoperative. Also, no protection exists against a vandal leaving an object between the lamp and photosensor to break the light beam, causing water to run continuously.
Ishikawa, U.S. Pat. No. 3,575,640 teaches an automatic water supply ststem including a capacity sensitive antenna for sensing the approach of a user to produce a valve actuator, signal for operating an electromagnetic valve to turn on a flow of water in a sink or urinal. A timer and delay circuit are included to shut off the water flow after a predetermined period of time.
Forbes, U.S. Pat. No. 3,670,167 discloses a system responsive to a decrease in the level of light supplied to one or two photocells as a result of a user approaching a wash basin, whereby the system responds by turning on a solenoid valve to initiate the flow of water into a basin. No provision is made for protecting against vandals leaving an object near the sink for making water run continuously into the sink. Also, although a user may not require water flow into the sinks, when his hands are away from the sink, water will continue to flow as long as the user or a non-user is close to the sink.
Lissau, U.S. Pat. No. 4,309,781 teaches a system for automatically flushing a urinal. The system includes a sensor assembly 10 consisting of a housing 12 enclosing an LED light source juxtaposed to a photosensor. A dark red filter is mounted in front of the LED and photosensor for reducing detection of ambient light reflections. The housing is mounted slightly above and behind the urinal. The LED 44 is excited by an oscillator 52 of fixed frequency. A user approaching the urinal causes infrared light from LED 44 to be reflected to photosensor 46. The output signal from the photodiode is connected to an amplifier 54 which is strobed by the signal from oscillator 52, for detecting only signals having the same frequency as light emitted from LED 44. The amplifier output signal triggers a timing circuit 58, which operates to turn on a solenoid valve 14, 161 when a user leaves the vicinity of the urinal, provided the user had remained in the vicinity of the urinal for at least the time period of timing circuit 58. The valve 16 is only turned on for a brief period of time, sufficient to flush the urinal 22.
Hill, U.S. Pat. No. 4,682,628 discloses a sensing and valve operating mechanism for remotely controlling a faucet which can be used with an anti-scald faucet valve and can be provided on a faucet by a kit. The mechanism senses the presence of an object near a faucet outlet, energizes a solenoid in response to the presence of an object, and calculates the time when the solenoid is energized. Energy is removed from the solenoid after a predetermined time interval notwithstanding that the presence of an object is still being sensed. The solenoid cannot be reenergized until after the object is removed from near the faucet outlet.
Notwithstanding the importance of the present problem, both as an individual matter and as a matter of national public interest, the sophisticated prior art devices cited above--which demonstrate and teach numerous alternatives for applying various electrical control systems to the flow of water and similar fluids--have in each case, various deficiencies. Some of the systems are either overly complex, or of a design that presents reliability problems. Also, certain of the above noted prior art, does not make adequate provision for the failure of the light source in a light source-photosensor pair, nor for the accidental or deliberate obscuring of the light source in a manner which would produce a wasteful flow of water, and waste of energy, or an overflowing of the sink.